THE BIOLOGY OF THE MUD-DAUBING WASPS 39 



of Hymenoptera. The bee 14 habitually uses the old cells for 

 her young. She divides them into smaller cells by partitions 

 of a waxy substance, making from one to five rooms out of each 

 original cell. Fig. 14 is a section of two abandoned cells of the 

 mud-dauber, revealing three pupal cases of Osmia cordata in 

 each. In the spring one finds these pupal cases (fig. 15) of 

 0. cordata in the cells, and occasionally a little pill of bee-bread 

 also. The opening of the old cell is thickly plastered with 

 the same brown, waxy substance (fig. 11.) The mother Osmia 

 also uses the old cells of the pipe-organ nests, plastering the 

 opening with a thick layer of wax, or even utilizes the hard 

 cocoon-shells of that species in the same way. Fig. 12 shows 

 these cells in use; a is a complete cell with the open end plastered 

 up with wax; b is the waxy plug removed showing the hole 

 at one side made by the emerging bee ; c is part of the cell opened 

 to show the pupal case containing the living organism; d is a 

 cell complete, sectioned to show the partitions made of waxy 

 substance, and the plug remains as it was placed over the opening 

 made by the mother Osmia. 



At what time of the year the Osmia fills the cells and oviposits 

 we do not know. The bee is a honey-gatherer, I am sure, and 

 not a parasite in any way. Our individuals kept in confinement 

 fed readily upon sugar water. We conclude, from the occasional 

 presence of the pellet of bee-bread in the cells, that the mother 

 places this food in the partitioned room and lays her egg upon 

 it. When we opened the cells on January 1, 1913, we found 

 the adults in each cocoon completely grown. The bee would 

 crawl about for a time and then when replaced in the nest would 

 gladly creep back into its broken cell. Those which were not 

 replaced were glad to get into any crevice. It seems that 

 during cold weather they remain in their enclosures even though 

 they are fully matured. If a bee is removed before its period 

 of hibernation is completed, it may be replaced in its torn cocoon, 

 or it often goes back into the shell or some other crevice of its 

 own accord and resumes its sleep without ill effect. But when 

 they emerge of their own accord (about the middle of April, 

 if out-of-doors, or in March in the living-room), they have not 

 the ability to rehibernate and soon die unless fed. 



These bees have the power of emitting a very pleasant, sweetish 

 14 Kindly identified by Mr. J. C. Crawford as Osmia cordata Robt. 



